/*
 * Copyright (C) 2008 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;

import java.io.Serializable;
import java.util.Map.Entry;
import java.util.Spliterator;
import java.util.function.Consumer;
import javax.annotation.CheckForNull;

/**
 * {@code values()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class ImmutableMapValues<K, V> extends ImmutableCollection<V>
{
    private final ImmutableMap<K, V> map;

    ImmutableMapValues(ImmutableMap<K, V> map)
    {
        this.map = map;
    }

    @Override
    public int size()
    {
        return map.size();
    }

    @Override
    public UnmodifiableIterator<V> iterator()
    {
        return new UnmodifiableIterator<V>()
        {
            final UnmodifiableIterator<Entry<K, V>> entryItr = map.entrySet().iterator();

            @Override
            public boolean hasNext()
            {
                return entryItr.hasNext();
            }

            @Override
            public V next()
            {
                return entryItr.next().getValue();
            }
        };
    }

    @Override
    public Spliterator<V> spliterator()
    {
        return CollectSpliterators.map(map.entrySet().spliterator(), Entry::getValue);
    }

    @Override
    public boolean contains(@CheckForNull Object object)
    {
        return object != null && Iterators.contains(iterator(), object);
    }

    @Override
    boolean isPartialView()
    {
        return true;
    }

    @Override
    public ImmutableList<V> asList()
    {
        final ImmutableList<Entry<K, V>> entryList = map.entrySet().asList();
        return new ImmutableAsList<V>()
        {
            @Override
            public V get(int index)
            {
                return entryList.get(index).getValue();
            }

            @Override
            ImmutableCollection<V> delegateCollection()
            {
                return ImmutableMapValues.this;
            }
        };
    }

    @GwtIncompatible // serialization
    @Override
    public void forEach(Consumer<? super V> action)
    {
        checkNotNull(action);
        map.forEach((k, v) -> action.accept(v));
    }

    // No longer used for new writes, but kept so that old data can still be read.
    @GwtIncompatible // serialization
    @SuppressWarnings("unused")
    private static class SerializedForm<V> implements Serializable
    {
        final ImmutableMap<?, V> map;

        SerializedForm(ImmutableMap<?, V> map)
        {
            this.map = map;
        }

        Object readResolve()
        {
            return map.values();
        }

        private static final long serialVersionUID = 0;
    }
}
